Add-A-Stack Shelving System Grows with filing needs. Add-on tiers or shelves stack separately, creating flexible, expandable shelving. Start with a top and baseadd as many tiers as needed. Each filing tier has four fixed dividers spaced 7" apart. Intended for use with open shelf filing supplies, but accepts standard file folders (not included). Assembly required. Top and Base Unit Order one unit for each stack of Filing Tiers, sold separately. Letter SizeTop and Base are each 36w x 13-3/16d. Sand